1. Field of the Invention
The present invention relates to a continuous process for laminating thermoplastic films to high heat capacity woven fabrics without the use of adhesives, to the resulting product and to apparatus for producing such a product.
2. Description of the Prior Art
Asbestos has generally been the material of choice for high-temperature applications such as protective clothing or wrapping. However, recently asbestos has been identified as a carcinogenic agent and therefore, alternative materials are needed for applications involving occupational safety.
High-temperature resistant fabrics have been developed by the aerospace industry such as carbon, graphite, boron and amorphous silica such as Refrasil which is a continuous filament flexible amorphous silica textile material with excellent insulation characteristics for high-temperature applications. However, these filaments and especially Refrasil are generally rough and abrasive, tending to bend, break and fray during weaving. Thus, fabrication by conventional methods of stitching, sewing, grommeting is not possible.
An obvious expedient to control these disadvantages would be to adhere a smooth continuous film to the surface of the high-temperature fabric. Generally adhesives have been utilized to laminate films to fabric. However, adhesives are an unnecessary non-refractory mass and would tend to melt and cause delamination in the environment of intended use thus lowering the maximum service temperature of the fabric. Furthermore, adhesives increase the cost of the final laminated product and also increase the flammability and the bulkiness of the product and decrease flexibility of the laminated film. Film or liquid adhesives also interfere with the production of fabric appearing products in that they are generally hazy, colored or prevent clear naturally looking coated products. Since adhesives tend to flow into the interstitial spaces of the woven web, after application of the continuous film, the fabric will tend to have a non-woven appearance rather than a woven fabric appearance.